The present invention relates to a heald supporting frame with composite structure for weaving looms.
As is known, heald supporting frames are used in weaving looms to support a plurality of healds, or heddles, each of which has a warp thread associated therewith. Said frames are constituted by rectangular structures which have a modest thickness, are as long as the maximum, width of fabric which can be processed on the loom for which they are intended, and are formed by two parallel cross-members, respectively an upper one and a lower one, to which the healds are coupled, and by a pair of side members which have the purpose of rigidly connecting the cross-members and must be easily removable in order to allow the insertion of the healds. The heald supporting frames are furthermore connected to a movement system which can move them vertically in order to achieve coordinated movements of the sets of warp threads connected to each frame, opening the pitch for the insertion of the weft according to the particular pattern to be provided in the fabric.
According to the known art, both the healds and the frames which support them are made of metallic materials in order to ensure adequate rigidity and solidity of the assembly. Since these are mechanical elements which perform a rapid or very rapid reciprocating motion, the current trend is naturally to make these elements using aluminum or light alloys in order to minimize their mass and thus their inertia. In order to maintain the necessary rigidity of the frame, this minimization cannot, in any case, exceed a certain limit, unless one uses special metallic alloys with low specific gravity and high mechanical strength, which however would increase the cost of the frame to excessively high levels.
A typical problem of known metallic heald supporting frames is noise. In fact, since the healds are coupled to the frame with a certain play, multiple mutual impacts between the frame and the healds occur during the movement of the frame, with metal-on-metal contacts which cause very high noise.
It has therefore been proposed to manufacture heald supporting frames made of different materials, particularly synthetic ones, but these proposals have not been able to achieve the intended aims of lightness and low cost at the same time.